The present invention generally relates to a transporter and method for transporting one or more persons, and more particularly, to a transporter whose sustained motion is controlled, at least in part, by leaning.
A prior art, dynamically balanced transporter 18 whose sustained motion may be controlled by a rider leaning, is shown, in one embodiment, in FIG. 1, which is described, along with other such transporters, in U.S. Pat. Nos. 5,701,965 and 5,971,091, both of which are herein incorporated by reference. Transporter 18 is statically unstable with respect to tipping in the fore-aft plane and requires a control loop to maintain dynamic stability. Transporter 18 includes a support platform 12 for supporting a person 10 over the ground or other surface. A handlebar 14 is attached to the support platform 12 for gripping by the person 10. Ground-contacting elements 13, which may be wheels, are movably attached to the support platform 12 and serve to suspend support platform 12 over the ground. The person 10 stands or sits on the support platform 12 such that transporter 18 of this embodiment may be operated in a manner analogous to a scooter. A control loop is provided so that leaning of the person 10 in a forward or backward direction results in the application of torque to wheel 13 about axle 15 thereby causing an acceleration of the transporter 18. The control loop actively maintains stability of the transporter 18, typically by keeping the center of mass of the vehicle above the point of contact of the ground-contacting elements with the ground, regardless of disturbances and forces operative on the transporter 18.
Another such prior art transporter whose motion is controlled by leaning is shown in FIG. 2, which is described, along with other such transporters, in U.S. provisional patent application Ser. No. 60/395,589, which is herein incorporated by reference. Unlike the transporter described in FIG. 1, transporter 20 in FIG. 2 is statically stable to tipping in the fore-aft plane. Transporter 20 includes a support platform 21 for supporting a person. Support platform 21 is flexibly coupled to wheels 23, 24, such that the attitude of the support platform 21 is capable of variation based on the load's center of mass relative to the wheels. Such variation may, for example, be caused by an operator leaning on the support platform 21. A sensor module 27, 28 generates a signal characterizing the attitude of the support platform. Based at least on the attitude, a controller commands sustained motion of transporter 20.
As discussed above, sustained motion of each of the above-described transporters may be controlled, at least in part, by a subject leaning on a support platform. However, a problem arises when there is more than one rider. While it may be relatively simple for a single rider to lean in a given direction so as to control the motion of the transporter, placement of a second person on the transporter may make it hard or impossible for either person to govern motion of the device by leaning.